1. Field of the Invention
The present invention relates to the field of plant breeding and, more specifically, to the development of tomato line CHI 15-2113, tomato line CHD 15-2114 and tomato variety BX 0154 3756.
2. Description of Related Art
The goal of vegetable breeding is to combine various desirable traits in a single variety/hybrid. Such desirable traits may include greater yield, resistance to diseases, insects or other pests, tolerance to heat and drought, better agronomic quality, higher nutritional value, enhanced growth rate and improved fruit properties.
Breeding techniques take advantage of a plant's method of pollination. There are two general methods of pollination: a plant self-pollinates if pollen from one flower is transferred to the same or another flower of the same genotype. A plant cross-pollinates if pollen comes to it from a flower of a different genotype.
Plants that have been self-pollinated and selected for a uniform type over many generations become homozygous at almost all gene loci and produce a uniform population of true breeding progeny of homozygous plants. A cross between two such homozygous plants of different varieties produces a uniform population of hybrid plants that are heterozygous for many gene loci. The extent of heterozygosity in the hybrid is a function of the genetic distance between the parents. Conversely, a cross of two plants each heterozygous at a number of loci produces a segregating population of hybrid plants that differ genetically and are not uniform. The resulting non-uniformity makes performance unpredictable.
The development of uniform varieties requires the development of homozygous inbred plants, the crossing of these inbred plants, and the evaluation of the crossed progeny. Pedigree breeding and recurrent selection are examples of breeding methods that have been used to develop inbred plants from breeding populations. Those breeding methods combine the genetic backgrounds from two or more plants or various other broad-based sources into breeding pools from which new lines are developed by selfing and selection of desired phenotypes. The new lines are evaluated to determine which of those have commercial potential.
One crop species that has been subject to such breeding programs and is of particular value is the tomato. The common tomato, Solanum lycopersicum (formerly Lycopersicon esculentum Mill.) is widely cultivated domestically and internationally. Of the approximately 500,000 acres of tomatoes grown annually in the United States, roughly 40% are grown for fresh market consumption, with the balance grown for processing.
Most cultivated tomatoes are diploid, self-fertile and mostly self-pollinating, with hermaphroditic flowers. Tomatoes having different ploidy levels are not uncommon and were already known in the 1920's and 30's (Linstrom, 1940). Prior to the mid-1970's, most commercial cultivars were pure breeding lines. Since then, better performing hybrid cultivars have been replacing the pure breeding lines. Today, most commercial varieties are hybrids. Due to its wide dissemination and high value, the tomato species has been intensively bred, providing a wide variety of lines with different traits. Tomato fruits from different cultivars show tremendous variation in weight and shape. Common groupings in the marketplace include the cherry, plum, pear, standard (or round), and beefsteak types.
While breeding efforts to date have provided a number of useful tomato lines and varieties with beneficial traits, there remains a great need in the art for new lines and varieties with further improved traits. Such plants would benefit farmers and consumers alike by improving crop yield and/or fruit quality.